1. Field of the Invention
This invention relates to a method for the on-site determination of the presence of corrosive material in lubricating oils through chemical analysis of the lubricating oil or samples thereof.
2. Description of the Prior Art
Oil used in lubricating machines or engines is subject to environmental parameters including, but not limited to, temperature, pressure and atmospheric conditions which result in chemical decomposition of the oil or degradation of the machines or engines themselves, having the effect of causing a buildup of corrosive material within the lubricating oil. This buildup requires that the lubricating oil be periodically monitored in order to determine the concentration of corrosive material present within the oil. As the concentration of corrosive material increases, the remaining usable lifetime of the oil decreases to the point where continued use of oil containing a high concentration of corrosive material is detrimental to the proper operation of the machine or engine thus necessitating removal of the lubricating oil from the machine or engine and replacement with oil containing a low concentration of corrosive material. Conversely, changing the lubricating oil too early in its operating lifetime results in significant and unnecessary expense.
Methods existing prior to the invention described herein for determining the concentration of corrosive material in lubricating oils and generally described in ASTM Procedure D-664 Potentiometric Analysis have utilized chemical procedures performed by chemists or highly skilled technicians at a laboratory, all at a great cost of time and money.
For example, machines or engines used to power oil drilling equipment utilize many gallons of lubricating oil. It is standard practice of oil manufacturers to add to the oil active anticorrosive materials which tend to inhibit the buildup of acidic corrosive materials. As the machines or engines are operated, the concentration of anticorrosive additives is depleted to the point where they fail to perform the inhibitory function, thus resulting in discernible increases in the amount of acidic corrosive material existing within the lubricating oil.
Characteristically, the lubricating oil used in drilling machines or engines has an operational lifetime dependent upon the quality of the lubricating oil, method of operation of the machines or engines and the environmental parameters to which the lubricating oil is subjected. Failure to replace lubricating oil that contains a high concentration of corrosive material causes damage to the machines or engines themselves and results in very significant repair and replacement costs.
The current methods of analyzing such oil require that samples of the oil be sent to laboratories far removed from the drilling site. Since the machines or engines used in the drilling operations are operated continuously, it is essential that information regarding the quality of the lubricating oil be transmitted to the drilling site as quickly as possible to avoid the possibility that the lubricating oil then in use within the machines or engines has exceeded its useful lifetime. As often is the case, current laboratory analyses of the lubricating oil at a place far removed from the drilling site requires a time in excess of the usable lifetime of the lubricating oil. This extended time period is due to the time involved in withdrawing a sample of the oil, sending it to a laboratory, analyzing the sample and transmitting the results back to the drilling site. Because of this time delay, the standard practice in the oil drilling industry is to replace the lubricating oil after an established operational lifetime dependent upon the operational and environmental parameters existing at the drilling site and without regard to the concentration of corrosive material within the oil. A drawback of this standard practice is that very often the oil is replaced before the concentration of corrosive materials is sufficiently high to warrant such replacement and contributes an unjustified expense to the cost of the entire drilling operation.
A feature of this invention over that of the prior art is to provide a reliable, simple and inexpensive method of on-site determination of the presence of corrosive material in lubricating oil.
A further feature of this invention is to provide a means of on-site determination of the presence of corrosive material in lubricating oil whereby the freshly removed oil, is dissolved in a solvent of selected composition with the resulting mixture being titrated to selected pH values with titrants of predetermined concentration; the volume of the titrants used to achieve the selected pH values then being measured and, subsequently, the measured volumes, together with that measured volume used to titrate a blank, being used to generate signals functionally related to the measured volumes and indicative of the quantity of the corrosive material present in the lubricating oil.